INCORPORATION OF INTERNAL FLUCTUATIONS IN A MEANDERING PLUME MODEL OF CONCENTRATION FLUCTUATIONS

A meandering plume model that explicityly incorporates the effects of small-scale structure in the instantaneous plume has been formulated. The model requires the specification of two physiclaly based input parameters; namely, the meander ratio, M, which is dependent on the ratio of the meandering plume dispersion to the instantaneous relative plume dispersion and, a relative in-plume fluctuation measure, k, that is related inversely to the fluctuation intensity in relative coordinates. Simple analytical expressions for crosswind profiles of the higher moments (including the important shape parameters such as fluctuation intensity, skewness, and kurtosis) and for the concentration pdf have been derived from the model. The model has been tested against some field data sets, indicating that it can reproduce many key aspects of the observed behavior of concentration fluctuations, particularly with respect to modeling the change in shape of the concentration pdf in the crosswind direction.